“GM is committed to reducing carbon emissions and reliance on petroleum,” Stephens said.

If that’s true it couldn’t have found a better company to make that vision come true than the pioneer of the “solar tree.” Envision produces solar systems for parking lots, whole “groves” of them to provide shade for cars while also gathering renewable energy. The tie-in to electric cars is so logical it’s ridiculous. The solar array can create a grid-free “island” that charges electric vehicles with zero emissions.

According to Desmond Wheatley, president and CEO of San Diego-based Envision Solar, the GM plan includes two models: A six-parking-space model with charging technology from ECOtality and enough solar power to recharge six Volts, and a single-tree “socket” version, a “sapling” capable of handling one Volt. The chargers are not exclusive to GM; modified versions are likely to be at other dealerships, and Envision has worked with a variety of charging company partners.

According to Wheatley, the solar tree is actually cleaner than, well, a real tree. I challenged him on that because it sounded sacrilegious to the Earth gods, but he made a good case for the solar tree offsetting more greenhouse gas than the real tree.

Another cool innovation is tracking -- the solar panels follow the sun as it moves across the sky, increasing electricity production 18 to 25 percent, increasing the output of a grove from 15 to 19 kilowatts. “We spent a lot of time engineering that,” Wheatley said. “It moves up and down, but the corners stay in place because it’s important not to hit anything in a parking lot.”

GM and Envision will be showing off a solar-connected Volt at the California Center for Sustainable Energy in San Diego on Wednesday, and the road trip will move on to the Los Angeles Auto Show next month. Wheatley isn’t putting a price on his single-car tree, but it will be offered in a residential version soon. He said solar systems typically have a 10- to 15-year payback window, and his is expected to be no different.

Wheatley described solar charging as “a huge paradigm shift,” and pointed out that nearly everyone who hears about the solar trees thinks they’re a good idea. I totally agree. They’re a no-brainer, an idea so sensible and obvious I wish I’d thought of it.

The next step: Solar groves at big box stores that, like Best Buy, are stepping forward to offer electric vehicle charging in their parking lots. Adding solar to that is an idea without a downside.

Let me close by pointing out that I spent the morning at the rollout of the first fuel-cell car refueling station in a Maine to Florida "hydrogen highway" funded by entrepreneur Tom Sullivan of Lumber Liquidators. Guess what? The whole network will be solar powered.